Radiant Heating Pipe Variable Diameter Flow
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Solution Overview
Problem
Existing radiant heating tubes with double-P structure designs experience non-uniform temperature distributions and high CO and NOx emissions, which are undesirable in industrial furnace heating processes.
Innovation Solution
A radiant heating tube design featuring a middle section with varying diameters along its axial direction, forming a loop with return sections, allowing for controlled exhaust gas recirculation and heat distribution, which reduces CO and NOx emissions and achieves a more uniform temperature distribution by converting dynamic pressure to static pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a constant diameter middle section is used in double-P radiant heating tubes, then the structure is simple and easy to manufacture, but non-uniform temperature distributions occur and CO/NOx emissions increase
Solution Approach 1:
The middle section of the radiant heating tube is designed with variable cross-sectional area, where the cross-sectional area at the zone close to the burner is smaller than the cross-sectional area at the zone remote from the burner. This local variation in geometry creates different flow characteristics in different zones, improving temperature distribution uniformity and reducing harmful emissions without requiring complete structural redesign
Solution Approach 2:
The patent changes the geometric parameter (cross-sectional area) along the axial direction of the middle section. By making the cross-sectional area vary from the burner zone to the remote zone, the flow velocity and pressure distribution are optimized, leading to better combustion efficiency and reduced CO/NOx emissions while maintaining manufacturing feasibility
2Ease of manufacture
If a constant diameter middle section is used in double-P radiant heating tubes, then the manufacturing process is simple, but temperature peaks occur at the beginning of the central portion
Solution Approach 1:
The middle section employs different cross-sectional areas at different locations: a smaller cross-sectional area near the burner and a larger cross-sectional area remote from the burner. This local differentiation addresses the temperature peak issue by controlling the exhaust gas flow velocity and heat distribution in the critical near-burner zone, while keeping the overall structure manufacturable
Solution Approach 2:
The patent introduces variation in the cross-sectional dimension along the axial direction, transforming the middle section from a uniform cylindrical structure to a tapered or variable-section structure. This dimensional change affects the flow dynamics and heat transfer characteristics, eliminating temperature peaks while maintaining structural simplicity for manufacturing
3Object-generated harmful factors
If the middle section has a smaller cross-sectional area throughout, then CO and NOx emissions are reduced, but the structure becomes more complex and harder to manufacture
Solution Approach 1:
Instead of uniformly reducing the cross-sectional area throughout the middle section, the patent applies a localized approach: the cross-sectional area is smaller only at the zone close to the burner and larger at the zone remote from the burner. This localized geometric modification achieves emission reduction where it is most needed while avoiding unnecessary structural complexity elsewhere in the system
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The design results in reduced CO and NOx emissions and a more uniform wall temperature distribution, enhancing the efficiency and environmental performance of radiant heating tubes.
Implementation Method 1
converting dynamic pressure to static pressure
Implementation Method 2
Combustion takes place inside the radiant heating tube and the resulting heat is transferred to the material to be heated by thermal radiation
Implementation Method 3
it can, for example, heat up the supplied air
Data Source
Figure 1
Figure 2
AI summary
Provision is made of a radiant heating pipe 10 which is designed to conduct hot gas through a central portion 14 in a preferred direction of flow SV, directed away from the burner 22, into at least one return portion 16, 18 and preferably at least partially back into the central portion 14, such that a recirculation flow through the radiant heating pipe 10 is produced overall. The smallest flow cross section DA for the gas in a zone 24, close to the burner, of the central portion 14 is smaller than the smallest flow cross section DE in a zone 26 remote from the burner. Preferably, the radiant heating pipe 10 according to the invention has a waist at the transition from a branching portion 13, close to the burner, to the central portion 14.